Virtual Colonoscopy - Topic Overview
drinking clear liquids 6 to 8 hours before the colonoscopy. Your doctor may
have you use an enema 30 to 60 minutes before the test to completely cleanse
your colon. Your doctor also may give you specific instructions before your
test that take into consideration your health, age, and other medical
conditions you may have.
How is it done?
Virtual colonoscopy may be done in
a doctor's office, clinic, or a hospital. The test is most often done by a
doctor who specializes in performing and interpreting diagnostic imaging tests
(radiologist). The doctor may also have an
You will need to take off most of your clothes. You
will be given a gown to wear during the test.
First, you will be
asked to lie on your back. Air (or in some cases, carbon dioxide) will be used
to expand your colon. This helps the doctor see all parts of your colon. The
air is added using a tube placed in your anus. It may be uncomfortable when the
air is put into your colon. You may be given medicine to help the muscles in
your colon relax.
You will be asked to hold your breath while the
pictures of your colon are being taken. If you can't hold your breath for the
whole time, the doctor may need to take pictures a couple times in order to get
the whole colon. You may be asked to roll over and lie on your stomach. The
doctor will ask you to hold your breath again and pictures will be taken with
you lying in this position.
The test usually takes about 15 to 30
How does a virtual colonoscopy differ from a regular colonoscopy?
Virtual colonoscopy has advantages and disadvantages
compared to a regular colonoscopy.
- Virtual colonoscopy is less invasive, safer,
and takes less time than a regular colonoscopy.
- A thin tube to
insert air into the colon is placed in the rectum rather than a long flexible
tube that is moved up your colon. (But there is usually some discomfort
when the air is inserted.)
- No medicine to relax or sedate you is
needed, so you will be able to drive yourself home and resume normal
- Virtual colonoscopy may not show polyps
smaller than 10 mm (0.4 in.).
- You will need to hold your breath for short periods
of time while the computed tomography (CT) scanner takes pictures of your
colon. CT scanning will need to be done twice: once while you lie on your back
and then again while you lie on your stomach.
- Virtual colonoscopy
is not covered by all health insurance plans; check with your insurance plan
before having the test.
- Virtual colonoscopy is done in the
radiology department and involves a small amount of radiation
- If a polyp is found, regular colonoscopy will be needed
to confirm the diagnosis and remove the polyp so it can be looked at under a
microscope. If you can't have a regular colonoscopy the same day, you will
need to do another bowel preparation before the colonoscopy.
What do I need to consider about a virtual colonoscopy?